Hydraulic riveter



Sept.; 21, 1943. Y Hi R. FISCHER 2,329,709*

'HYDRAULIQ RIVETER'.

Filed Nov. 23, 1949 .4 sneetssneet 1 www@ l Patented Sept. 2l, 1943 HYDRAULIC BIIVETER n l yHoward R. Fisoher,Detroit, Mich., assigner to Chicago Pneumatic Tool Company.-New York,

N. Y., a corporation e! New Jersey` Application November y23, 1940, Serial No. 366,793

4 Claims.

This invention relates generally to compression riveting and like machines and more particularly toen.' assembly of this class comprising a power generating unit and a plurality of se f, "8

lectively operable riveting unitsl connected to the power unit.

The principal object of the invention'is toY obtain such independent pressure control oi the several riveting units as to enable each unit to deliver a maximum pressure different from that delivered by the other units.

Another object o f the invention is to enable the maximum pressure capabilities of 'each rivzeting unit to be varied without atlecting the pressure capabilities oi any other unit.

A more specinc object of the invention is to control the pressure developing means oi' the power unit through a valve assembly comprising' y a plurality of independently operable valves each adapted when actuated to disable the prese sure developing means, and each controlled by the iluid pressures within a respective riveting unit. v

. other objects and structural details of the xnvention will be more apparent from the following description when read in conjunction with the' accompanying drawings. wherein is gripped between stationary and movable dies I4` and I5, and set, while during the second stage the pressure acting on the movable die Il is intensiiied and the rivet' thereby headed. Restoration of the parts to normal is accomplished automatically when a predetermined pressure is reached within the riveting unit.

Except for the novel features of the present invention-the assembly disclosed herein is similarin construction and mode of operation to the assembly disclosed and claimed in the application by H. R.- Fischer and E. W. Stevens, Serial No.v305,204, illed November i8, 1939. 'I'he principal elements oi the old assembly and their general operation are described briefly below. In -this slunmary reference is had to only one riveting unit. e

Referring to the diagrammatic drawings, Figs. 2, 3 and 4. the movable die, lor rivet set, IB is illustrated as formed integrally with a pressure responsive piston I8 movable within a chamber Il in the riveting unit. Opening into the oppo- F'lg. 1 is a perspective view of a riveting assembly of the class described, embodying the mechanism of the invention;

Figs. 2, 3 and 4 are diagrammatic viewsshowing the assembly in its respective normal, intermediate, and fully actuated.- positions voi operation; and

Fig. 5 is -a detail diagrammatic view, of vim.I

automatic control elementf'and the valve assembly of the invention, showing one of the valves comprised in the assembly in actuated position.

A riveting assembly embodying the invention is shown in Fig. 1 a'nd is seen to comprise a power generating unit I0, and a pair of riveting' units Ii and I2 connected to the power unit by separate sets of flexible iluid conducting hose lines. 'Ihe units II and I2 are adapted for manual manipulation, independently of the power unit, and are selected for use alternatively according to the requirements of the work.

'There may be more than two riveting units, if

desired. The power unitv I0 operates under the remote control of a trigger I2, one of which is located in each unit II Aand I2, and, during a cycle of operation, delivers oil, or other hy draulic fluid, in two stages of pressure to a selected one of the riveting units. During the sitel ends of the chamber Il areI passages I! and I8 through which oil is supplied to the chamber to eect reciprocation of the piston I6. The passages I8` and I9 communicate through associated hose lines 2| and 22 with respective passageways 22 and 24 in the base ofthe power unit I0. The passageways 23 and 24 serve as outlets for a pair of oil reservoirs 28 and 2l and communicate therewith through respective intermediate piston chambers 2'! and 28. Thus. a column of oil originating in the reservoir 2B may be forced from the 'outlet 22, through the hose lline 2i and supply passage I8, to the rear oi' chamber I1 where it acts on the rivet set piston I6 in a direction to drive it toward the stationary die I4. Similarly, a column oiv oil orig#- inating in the reservoir 28 may be forced from the outlet 24, through the hose line 22 and supply passage I9 to the front of chamber Il to eect a return movement of the piston I8 away a passage 32 and oil is forced into the commu..

iirst, or low pressure, stage of the cyclethe rivet nicating lower end of the pressure chamber 2l where it actuates a piston 2l to drive the oil ahead oi the piston to the outlet 24. Asshown Air is ad- 'valve 35 closes the ports 34 during actuation of the piston. While the pressure of compressed air acting on the surface of the oil in reservoir 25 is suflicient to move the die |5 into engagement with the rivet itis insuillcient to cause the die to upset or head the rivet. Therefore, the pressure developing means includes a booster device in the form of a piston 38 the stem of which extends into the pressure chamber 21 for the purpose of intensifying the pressure of the oil flowing from outlet 23. The relatively large head of the piston 36 moves within a chamber 31 to the upper end of which air may be directed through a passage 38. Operation of the piston 38 serves to force `the oil from chamber 21 with great pres-` sure, which pressure is transmitted to the riveting piston i6 through the passages connecting chamber 21 to the rear of piston chamber I1. In the normal retracted position of the piston 38 (Fig. 2) the lower end of the stem thereof lies just above the point of communication between chamber 21 and passage 3|. Thus, preparatory to actuation of the intensifying piston, the chamber 21 and connecting passages may be filled with oil and the movable die l5 brought into contact with the rivet by admitting air to the reservoir 25. To return the piston 36 air is introduced into the front of the chamber 31 through a passage 39, this passage being a branch of the previously mentioned passage 32. A pressure reducing valve assembly 4| is disposed in the passage 38 to effect a saving of compressed air. i y

, The flow of air to the reservoirs 25 and 28 and the large compression chamber 31 isl controlled by a distributingsystem acting to initiate automatically the several steps of a riveting operation. Included in the distributing lsystem is a feed line 42, to which compressed air is constantly supplied, and a valve mechanism comprisinga distributing valve 43, and a pair of valves 44 and 45,

termed the preflll and automatic return, Valves for reasons whichwill hereinafter more clearly appear. The valves 43, 44 and 45 are shiftable longitudinally within respective bushings 48, 41 and 48 and settable to a plurality of control posichamber. When air is introduced within the chamber 55, below the valve 44, the pressure therein increases and tends to balance the pressure above the valve. When approximate equal- 1ity of balance is attained, a spring 51 forces the valve upward, this movement being retarded by reason of the necessarily slow displacement of air through the narrow opening around the upper ing 4.8 near the upperend thereof. In the uppermost position (Fig. 4) of the distributing valve 43, the air from passage 59 is admitted to the interior of the' bushing 48 and directed around a reduced portion 8| of the valve and out another set of ports to the passage 38.

The variable adjustment of the distributingv valve 43is obtained by unbalancing the air pressures at the opposite endsA of the valve. A cham.-

l and chamber 62.

berA 82 encloses the upper end of valve 43 and bushing 46, and receives live air through a passage 53 connected to the supply line 42 through a series of ports and passages controlled by the automatic return valve 45. A passage leads from the supply line 42 and communicates through a branch 65 and set of ports 88, in the bushing 48, with the interior of thebushing. In the normal lower position (Fig. 2) of the valve 45 a reduced portion 88 thereof lies opposite the ports 66 and air from passage 84 passes around the valve and out a port 81 to the passage 63 The air pressures above and below the valve 43 being thus normally balanced, a spring 88 is provided in the chamber 5| to urge the valve to the downward position of Fig. 2. In this position of the distributing valve the pas,-

sages 29 and 38, leading respectively to the reservoir 25 and the upper end of piston chamber 31, are closeduwhile ,passage 32 and branch 38 thereof are open to hold lthe respective pistons' I8 and 35 in retracted position. If, now, the pressure in chamber 82 above valve 43 be reduced,

tions with respect to passages leading from the supply line 42. One passage so controlled is indicated at 49 and is seen to open into a chamber 5| /receiving the lower end of distributing valve 43. A branch52 of passage 49 registers with a set of ports in bushing 48, and, in the normal position (Fig. 2) of valve 43, directs air around a reduced portion 53 of the valve, and through another set of bushing ports to the passage 32 leading to the return oil reservoir 26. Also, the valve 43 serves normally to close the bushing ports connecting the chamber 5| to a passage 54. The

the lower end of prefill valve 44 and'is in constant communication with the passage 29 leading to the reservoir 25. Upon movement of the valve 43 upward to the positions of Figs. 3 and 4 the passage 54, chamber 55 and passage 23 are connected to the live air source through the cham- 'ber 5|. The passage 38, leading to the intensifier chamber 31, is controlled jointly by the distributing valve 43 and the preilll valve 44. The valve 44 is normally held in the lower position of Fig, 2 by the pressure of air above the valve delivered there by a live air conduit 56 through a narrow opening separating the upper end of the valve bushing 41 from the wall of the enclosingvalve passage 54 leads to a chamber 55 .surrounding Y the valve will be forced upward against the pressure of spring 68. A movement of the valve from Fig. 2 position to the intermediate position of Fig. 3 and fully actuated position of Fig: 4 serves to cut off the passages 32 and branch 39 from the live air source and to permit the flow of air from chamber 5| through passage 54 to chamber 55 and passage 29, leading to reservoir 25. At this time the preflll of the passageways leading w the rear of riveting unit chamber |1 takes place and continues during the period that the preill Valve-44 is moved upward by spring 51. When the-valve 44 reaches the open position of Fig. 4 air flows from the conduit 56 to the passage 55 and 4is permitted to pass aroundthe valve 43 to the passage 38 if this valve has reached fully actuated position. It will be noted that in the intermediate position of Fig. 3 the distributing valve has not reached open position with respect lto passage 59 so that air may not be directed to .be ineffective until the valve reaches intermediate position. At this point the for'ce of the auxy iliary spring 69 supplements that of the spring 68 in urging the valve 43 downward. Thus, a greater disparity in pressure at the opposite ends of the valve 43 is necessary to move the valve from intermediate to fully actuated position than is required to move it from normal to intermediate position.

Pressure reductions withinthe chamber 62 are brought about through exhaust means controlled by the trigger I3 on the riveting unit. The previously mentioned passage 64, leading from supply line 42, is also connected to an. air hose 1I placing the supply line in communication with a passage 12 inthe riveting unit. 'A valve 13 is -disposed within the passage 12 and is movable by trigger I3 to open position with respect to-an exhaust port 14. When the valve 13 is actuated by triggerA I3 the air flowing to the riveting unit is free to pass to atmosphereV through the port- 14. Within the passage 64 and placed between the branch passage 65 yand supply line 42 is a" metering valve 15 Iwhich substantially reduces the' rate of air now to the chamber 62 and the riveting unit. Therefore, when exhaust valve 13 is opened the air escapes from port 14 more rapidly than it can pass'through metering valve 15 with the result that a drop in pressure occurs in the 'air lines between the metering valve and the riveting unit. Chamber 62 communicates lwith passage 64 at a. point within the area of reduced pressure so that the pressure drop is reflected also in the ports and passages leading to the chamber, and ln the chamber itself. The extent O1' pressure reduction in chamber 62 is determined by the extent of actuation given the trigger I3. In initiating a cycle of machine operation the trigger may be fully actuated in' a single motion or' it may be momentarily held in the partly actuated position of Fis.A 3 before completing the full stroke. In the latter instance the initial movement of the trigger will permit movement of the distributingvalve '43 to its intermediate position but the pressure drop in chamber 62 Will be in'- suilcient to overcome vthe combinedl opposing pressures of springs 68 and 69. The'valve will remain in intermediate position, therefore, until the trigger I3 is fully actuated and the pressure in chamber 62 thereby further reduced.

In terminating a cycle of operation the return valve 45 is moved upwards from the position shown in Figs. 2, 3 and 4 to the position shown in Fig. 5. This movement is accomplished against the pressure of a spring 16 and serves to place a lower reduced portion 11 of the valve opposite a port 18 aligned with a passage 19 leading from supply line 42. Air at line pressure immediately passes around the valve 45 and out a port 8l communicating with passage 63 and chamber 82. The chamber 62 being thus supplied with live 'air the pressure therein rises and quickly equals that within chamber I, whereupon the springs 68 and 89 return the distributing valve 43 to the lower normal position of Fig. 2. This movement serves to cut oil' the flow of pressure fluid to the passages 29 and 38 and re-establishes the iiow through passage 32 and branch 3 9'to restore the pistons I6 andv 36 to their/retracted positions. Movement ofthe return valve 45 to upper position takes place automatically while the trigger I3 is held actuated and is initiated by means forming a part of the invention. This means includes a pressure fluid conducting passage 82 opening into the area. surrounding the lower end of the valve 45 and controlled-by a valve assembly 83 later to be described.

Pressure from the passage 82 is applied only momentarily to the lower end of the return valve 5 and it is desirable that an auxiliary holding pressure be introduced below the valve in order that the valve may not return to normal prematurely and initiate automatically a second cycle of oD- eration. Holding pressure for this purpose is applied through a longitudinal bore 84, in the lower end of valve 45, to which air is admitted through an opening 85 located in reduced portion 11 of the valve. Thus, live air from the auxiliary passage 19 is directed also below the valve 45 and prevents return of the valve by spring 16. As shown in Fig. 5, while the valve 45 is held in acv tuated position the upper reduced portion 68 thereof connects the upper one of the pair of ports 66 to apassage 86 opening into the area 20 surrounding the upper lend of the valve. By this tuated position as long as the exhaust valve 13 is held open. Upon release of the trigger I8, however, the'exhaust valve closes and the pressure in hose line 1I and connecting passages rapidly builds up to full line pressure, whereupon the air pressures at the opposite ends of the valve 45 are balanced and the spring 16 is permitted to return the valve downward to normal position. It is apparent, therefore, that if the operator holds the control valve 13 open longer than necessary, the riveting piston I6 will be restored to normal 'position but-will not start on a new power stroke until the operator closes and then reopens the valve 13. y 40 The selection of one or the other of the riveting units II and I2 for use is performed by manual manipulation of a two-way valve assembly -81 (Fig. l) comprising separate valves 88 and 89 i (Figs. 2-4). The valve 88 controls the flow of oil from the high pressure outlet 23 and operates in a conventional manner to connect one or the other of the hose lines 2| to the outlet.

valve 8,9 is interposed between the compressed air supply line 42 and the riveting units I I and I2 and is settable like valve 88 to direct air alternatively to the units. Both of the-hose lines 22 may be open constantly to receive oil from the return reservoir 26.' In the drawings, the

' valves 88 and 89 are set to condition the unit I2 for operation.

In the riveting assembly disclosed in the prior application above identified a means is provided for actuating the automatic return valve 45 when a predetermined pressure is reached within the intensier chamber 81. This method of initiating the return stroke, while generally satisfactory, has the disadvantage of limiting both riveting units II and I2 t0 the same peak pressure.

Thus when changing from one riveting unit to,

The

through passage 82 to the iowerend of returnv valve 45. The shank or stem or each valve 9I and 92 is formed as a plunger and has a sliding t within its respective bore 93 and 94. Opening into the lower end of the bores 93 and 94 are respectlve passages 99 and IIII communicating at their opposite ends with the high pressure oil hose lines 2|, the passage 99 being connected to' the hose line associated with riveting unit II while passage IUI is connected to the hose line associated with unit I2. During the prefill op-l eration, therefore, one of the passages 99 or IM is filled with oil andthe subsequent intensified pressure-delivered through the hose line 2l .is reilected also in the communicating passage 99 or IIiI. When the pressure Within this passage becomes suiiiciently high to unseat its associated valve 9| or 92, live air is permitted to pass from the supply line 42 to the area below the valve Il whereby this valve is shifted upward and the return stroke initiated in the manner previously described. The valves 9| and 92 may thus be termed pressure relief valves since their operation terminates the application of intensiiied pressure within the riveting unit. Actuation of the relief valves is resisted by the springs 91 and 99 and the pressure of these springs may beindependently increased or diminished at will through adjustment of respective associated set screws |92 and |93. Thus, a variable resistance.

may be imparted to each valve 9| and 92. By way of example the valve 9i `might be caused to resist actuation Auntil a pressure of 5,000 pounds per square inch is reached in the piston chamber II of unit I-I, while the valve 92 is set for actuation when the pressure Within unit I2 reaches 1,250 pounds per'square inch. l

The above pressure control mechanism is y shown also in Fig. l where the pressure reliefv valve assembly 93 is shown mounted on the head of the power unit I0. The passages 99and- IIlI 4are represented, in this embodiment of the invention, as pipe lines arranged outside the unit and connected to the hose lines 2I beyond the two-way valve assembly 91. The passage 95 for conducting live air to the valve assembly 99 is also indicated as a conduit outside the unit. While the 'invention has been disclosed with particular reference to a riveting machine, it is susceptible of embodiment in machines for other uses, such as pressing, pulling, crushing, punching and embossing.

What is claimed is:

1. A riveting assembly, comprising a hydraulic system for eiecting operation of said assembly,

said system terminating in separate-pressure iluid conduits, a pressure fluid operated booster de vice within said hydraulic system, means for terassavoo lease the'pressure' in said system. said means including a control element adapted when actuated to condition said means for operation, a passageway leading to said control element to permit actuation of said element by the force oi pressure fluid, 'a valve assembly controlling the ilow of pressure iluid through said passageway, said assembly comprising a plurality of independently operable valves` each adapted when operated to open`said passageway to the flow of pressure iiuid, and pressure responsive means associated with each of said valves and communicating with a respective one of saidl separate pressure iiuid conduits for operating said valves.

2. A riveting assembly according to claim 1 .characterized by independently operable means associated with each of said valves for imposing a variable resistance to the operation thereof.

3. A riveting assembly, comprising a plurality of piston chambers, a source of pressure fluid,

separate pressure fluid'conducting lines leading from said source to said piston chambers, a booster device for intensifying the pressure in said fluid lines and thereby in said piston chambers, settable means for controlling said booster device adapted in a rst position to initiate operation of said device and in a second position to terminate operation of said device, pressure fluid means for moving said settable means to its said second position, a pilot valve for controlling said pressure iiuid means, and pressure responsive independently operable means communicating with each of said piston chambers for initiating actuation oi said pilot valve when the pressure in its associated piston chamber reaches a predetermined peak.

4. A riveting assembly, comprising a plurality of piston chambers, a source of pressure fluid, separate pressure fluid conducting lines leading from said source to said piston chambers, a pres- 'sure fluid operated booster device for intensifying the pressure in said iiuid lines and thereby in said piston chambers, a distributing valve having a normal position in which it disconnects said fluid lines from the pressure fluid source and prevents the supply oi' iluid to vsaid booster device. said distributing valve being settable in step by-step fashion to rst and second positions and acting on the iirst step to connect said fluid lines to said pressure iluid sour'ce and acting on the second step to admit pressure duid to said booster.

,minating operation of said booster device to redevice, means for returning said distributing` valve to normal in a single step to release the pressure in said fluid lines, a control element adapted when actuated to initiate return movement of said distributing valve, pressure iluid means for actuating said control element, a. valve assembly controlling the now of pressure iluid to said control element, said assembly comprising a plurality of independently operable valves each adapted when operatedto permit the iiow of iluid to said control element, and pressure responsive means associated with each of said valves and communicating with a respective one of said piston chambers for operating said valves.

HOWARD R. FISCHER. 

